<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>圆角边框</title>
</head>
<style>
    div{
        width: 500px;
        height: 500px;
        border: 1px solid black;
        margin: 0px auto;
        /*border-top-left-radius: 50px;*/
        /*border-top-right-radius: 80px;*/
        /*border-bottom-right-radius: 100px;*/
        /*border-bottom-left-radius: 20px;*/
       border-radius: 50px 80px 100px 20px; /*上面四个的缩写*/
    }
</style>
<body>
<div>

</div>
</body>
</html>